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The IUCN has classified the Mediterranean sperm whale population as “endangered”, with collisions with boats being one of their main survival problems. The Balearic Islands are a unique enclave of the species in the basin, which is why an IMMA area has been declared in favour of its conservation. It is therefore essential to obtain the necessary data to assess this conflict and how it affects the viability of the population.

The general objective of the project has been to assess the evidence of collision in sperm whales by means of remote imaging, in the Balearic Islands.

• Description of the optimal technique for remote imaging.
• Remote imaging of sighted individuals.
• Management and screening of the generated image files.
• Viewing of the images for the determination of marks, nature and anatomical distribution.
• To determine the presence or absence of individuals in the catalogue of individuals in the Balearic Islands.
• Determine the ratio of affected individuals by gender class and age class.
• Geographically locate the individuals recorded according to class.
• Create maps of navigation densities and animal presence.
• Locate and determine risk areas.
• Dissemination and communication of the project.
• Remote device purchase management.

The development of the COLCA project has been based on the use of unmanned vehicles, drones and ROVs to obtain remote images of sperm whales.

• Once the methodology was fine-tuned, the images for the assessment of collision evidence taken between May and September 2020, have allowed the analysis of 62 individuals.
• In one of the specimens, a scar several centimeters deep, 35 cm long and 15 cm wide was evidenced compatible with a collision with a boat, which represents 1.61% of the individuals sighted.
• This data is significantly lower than that obtained in previous years by photography from a boat, where an incidence of the marks of around 10% was determined.
• In addition, other marks and skin erosions have been assessed by gender and age class.

• On the other hand, taking into account the model of expected presence of sperm whales and the data on the presence of ships from satellite data, a collision risk map has been drawn up , identifying the main areas where the threat to the species is greatest.

The development of the COLCA project has contributed to improving the information available for the management of collisions between ships and sperm whales, as well as to determine the suitability of the drone for the study of the species, both to assess the evidence of collision and to analyse other individual and social parameters, in order to improve its knowledge and therefore its management.